1. Field of the Invention
The invention relates to a high current power output stage comprising power transistors, in particular MOSFET power transistors.
2. Description of the Prior Art
High current power output stages are used, for example, in control units of motor vehicles for driving electric motors, e.g., for an electric power steering device or an electric brake force amplifier device. The high current power output stage is operated in a normal operation mode, e.g., with currents of the order of magnitude of 100 amperes. The electrical energy required is provided by a generator device or a battery. When the battery is replaced, the battery can inadvertently be coupled to the high current power output stage with the polarity reversed. The current flow caused as a result of this in the high current power output stage can damage or destroy the power output stage.
DE 102 08 981 A1 discloses a motor vehicle comprising two vehicle electrical systems. A current distributor with power management is provided for each of the two vehicle electrical systems. One of the current distributors comprises an output stage and a microcomputer. The output stage comprises a measuring resistor. The current flow in the output stage is determined from a voltage drop across the measuring resistor by the microcomputer. The current flow in the output stage can be interrupted by corresponding driving of the output stage by the microcomputer. A fusible link is connected in one supply line of the output stage in order to prevent a fire in the event of a short circuit and simultaneous breakdown at the output stage. A relay is provided as a polarity-reversal protection, said relay interrupting the current flow in the event of polarity reversal.
DE 195 01 985 A1 discloses a polarity-reversal protection for a DC-voltage-supplied electronic circuit against damage as a result of polarity reversal. A suppressor diode is connected in parallel with a battery and with electrical loads. A fusible link is connected in a supply line between the battery and the suppressor diode and the electrical loads. In the event of polarity reversal, the suppressor diode is turned on and the fusible link triggers as a result of the current flow caused thereby.